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Record information about sections of emitted code+data.

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The result of the emitter is a vector of bytes holding machine code,
jump tables, and (in the future) other read-only data.  Some clients,
notably Firefox's Wasm compiler, needs to separate the machine code
from the data in order to insert more code directly after the code
generated by Cranelift.

To make such separation possible, we record more information about the
emitted bytes: the sizes of each of the sections of code, jump tables,
and read-only data, as well as the locations within the code that
reference (PC-relatively) the jump tables and read-only data.
This commit is contained in:
Lars T Hansen
2019-05-21 15:53:46 +02:00
committed by Lars T Hansen
parent 70f79d23bf
commit 420850adf0
12 changed files with 166 additions and 73 deletions
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34
cranelift/codegen/src/context.rs
View File

@@ -10,7 +10,7 @@
//! single ISA instance.
use crate::binemit::{
relax_branches, shrink_instructions, CodeOffset, MemoryCodeSink, RelocSink, TrapSink,
relax_branches, shrink_instructions, CodeInfo, MemoryCodeSink, RelocSink, TrapSink,
};
use crate::dce::do_dce;
use crate::dominator_tree::DominatorTree;
@@ -93,20 +93,21 @@ impl Context {
/// This function calls `compile` and `emit_to_memory`, taking care to resize `mem` as
/// needed, so it provides a safe interface.
///
/// Returns the size of the function's code and the size of the read-only data.
/// Returns information about the function's code and read-only data.
pub fn compile_and_emit(
&mut self,
isa: &TargetIsa,
mem: &mut Vec<u8>,
relocs: &mut RelocSink,
traps: &mut TrapSink,
) -> CodegenResult<(CodeOffset, CodeOffset)> {
let total_size = self.compile(isa)?;
) -> CodegenResult<CodeInfo> {
let info = self.compile(isa)?;
let old_len = mem.len();
mem.resize(old_len + total_size as usize, 0);
let code_size =
mem.resize(old_len + info.total_size as usize, 0);
let new_info =
unsafe { self.emit_to_memory(isa, mem.as_mut_ptr().add(old_len), relocs, traps) };
Ok((code_size, total_size - code_size))
debug_assert!(new_info == info);
Ok(info)
}
/// Compile the function.
@@ -115,8 +116,8 @@ impl Context {
/// represented by `isa`. This does not include the final step of emitting machine code into a
/// code sink.
///
/// Returns the size of the function's code and read-only data.
pub fn compile(&mut self, isa: &TargetIsa) -> CodegenResult<CodeOffset> {
/// Returns information about the function's code and read-only data.
pub fn compile(&mut self, isa: &TargetIsa) -> CodegenResult<CodeInfo> {
let _tt = timing::compile();
self.verify_if(isa)?;
@@ -160,18 +161,18 @@ impl Context {
/// This function is unsafe since it does not perform bounds checking on the memory buffer,
/// and it can't guarantee that the `mem` pointer is valid.
///
/// Returns the size of the function's code.
/// Returns information about the emitted code and data.
pub unsafe fn emit_to_memory(
&self,
isa: &TargetIsa,
mem: *mut u8,
relocs: &mut RelocSink,
traps: &mut TrapSink,
) -> CodeOffset {
) -> CodeInfo {
let _tt = timing::binemit();
let mut sink = MemoryCodeSink::new(mem, relocs, traps);
isa.emit_function_to_memory(&self.func, &mut sink);
sink.code_size as CodeOffset
sink.info
}
/// Run the verifier on the function.
@@ -325,12 +326,13 @@ impl Context {
Ok(())
}
/// Run the branch relaxation pass and return the final code size.
pub fn relax_branches(&mut self, isa: &TargetIsa) -> CodegenResult<CodeOffset> {
let code_size = relax_branches(&mut self.func, isa)?;
/// Run the branch relaxation pass and return information about the function's code and
/// read-only data.
pub fn relax_branches(&mut self, isa: &TargetIsa) -> CodegenResult<CodeInfo> {
let info = relax_branches(&mut self.func, isa)?;
self.verify_if(isa)?;
self.verify_locations_if(isa)?;
Ok(code_size)
Ok(info)
}
/// Builds ranges and location for specified value labels.